We hypothesize that in comparison with OI subjects, the MTBI group will exhibit slowing of EEG frequency, alteration of cerebral white matter microstructure on diffusion tensor imaging (DTI), and cognitive deficit within 24 hours after injury. We also hypothesize that MTBI subjects will show recovery in their EEG frequency and cognition over six months following injury despite residual white matter injury on DTI. We will also collect two plasma samples and a saliva sample, the first within 24 hr of injury (baseline) and the second at six months post-injury, for measurement of potential biomarkers and genetic studies.